DE2349835A1 - MOLDING COMPOUNDS MADE FROM REINFORCED POLYAMIDES - Google Patents

Description

The invention relates to polyamides reinforced with mineral fillers and having improved surface properties.

It is known to use thermoplastically processable polyamides reinforce mineral fillers. This measure has a favorable influence on the rigidity, the hardness, the dimensions and the dimensional stability. For example, in DOS 1,520,392 such reinforced polymeric molding compositions described;

The disadvantage of such molding compounds, however, is that after processing, for example by injection molding, the surface of finished parts is uneven and has a matt appearance processing temperatures disappear, in which the polymers already decompose or where the polymer melt is so fluid already that unwanted injection molding so-called webbed created "the present invention was Datier the lufgafoe invention to develop reinforced polyamides with mineral fillers that add up to moldings can be processed with a perfectly shiny ^{1 surface *}

It is known from DBP 1 066 73β and DBP 1 197 615 that the surface of molded parts made of polyamides allowed the addition of small amounts, e.g. of imine derivatives or salts higher? Fatty acid © can be improved. In the case of foifaiaiöen reinforced with mineral fillers, however, these additives do not bring about any noticeable improvement in the surface _{or the like}

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Surprisingly, it has now been found that reinforced polyamides, the long- in addition to 0.1 to 2.0 percent by weight of metal salts. chain carboxylic acids still contain 0.5 to 4.0 percent by weight of lactams, when processed moldings with excellent Surfaces.

Suitable metal salts are, for example, salts of calcium, strontium, barium, zinc or aluminum with carboxylic acids with 8 to 20 Carbon atoms, preferably stearic acid. As' lactams those with 4 to 12 carbon atoms can be used, with caprolactam being preferred.

Polyamides in the context of the present invention are preferably semi-crystalline polymers that can be produced either by polycondensation or polyaddition from ω-aminocarboxylic acids or from the corresponding lactams or from aliphatic and / or aromatic diamines on the one hand and aliphatic and / or aromatic dicarboxylic acids on the other. Polycaprolaetarne (nylon 6) with a relative viscosity between 2.2 and 5.0 and polymers of hexamethylenediamine and adipic acid (nylon 6,6) with a relative viscosity between 2.2 and 5.4, each measured according to DIN, are particularly preferred 53 727 in sulfuric acid (9β #ig, c = 1.0 g / 100 ml solution at 25 ° C). When polyamides are produced by polyaddition of caprolactam, the reaction generally only proceeds up to a conversion of about 90 %. It is customary to subsequently remove the residual monomers by extraction. Technical polycaprolactam therefore always contains less than 0.5 % monomeric caprolaetam «,

As fillers can be natural, occurring and synthetic

are used, s »B _e calcium carbonates magnesium carbonates anhydrous aluminum silicates, calcium silicates, aluminum

e * TalkuiBä, Quaramsble and similar compounds on Silifcetfoasls * you. generally have mean particle sizes below IO0 / U _Ä vorzugsweise- swisohea 1 and 40 / U "The ratio Ling © zn bead ± l <sgfc here below 10: 1, preferably 'below VOA 4 § i" bie Füllstoff® with adhesion can mediate -> AEEN substances * as s _o B _e Organosiianen, preferably with

609017/0345 - -3-

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Aminopropyltriäthoxysilan be treated. The quantities of Fillers in the molding compositions are generally between 10 and 70 percent by weight, preferably between 20 and 40 percent by weight.

The molding compositions can contain conventional additives, such as stabilizers, Contains color pigments, flame retardants (e.g. according to DOS 1 808 130).

The surface-improving agents according to the invention can be incorporated in a known manner together with the fillers take place, e.g. by mixing with the polyamides and melting in an extruder. But you can also - and that recommended when working with polycaprolactam - from monomers freed, extracted polymer with unextracted (monomer content 9 to 10 percent by weight) in the desired ratio Mix and process together with the remaining components of the mixture.

The following example gives an overview of the achieved Effects.

example

On a single-screw extruder, the values given in the table are given premixed quantities of polyamide, fillers and lubricants melted and homogenized; the polymer melt is pressed out through a nozzle, drawn off as a strand, granulated and molded into small test boxes on an injection molding machine. In the table the injection molding temperature is given, in which the surface of the finished part is flawless, i.e. becomes shiny.

Experiments c, e, g and k are according to the invention. With those there At the processing temperatures mentioned, no degradation of the polymers occurs, while in the comparative tests already a discoloration and a strong appearance of webbed feet can be observed.

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O.ζ. 30 127

Tabel

attempt a polymer 6th filler b nylon 6th 30 # chalk C. nylon 6th 30 % chalk d
e nylon VO VD 30 % chalk 509817 f nylon
nylon 6th 30 % chalk with
Ca stearate coated
30 % chalk with
Ca stearate coated ο G nylon 6th 30 % calcined clay to nylon 30 % calcined clay

Additives

good surface at processing temperatures

Nylon 6,6 30 % quartz powder treated with adhesion promoter / aminopropylsilane

Nylon 6,6 30 % quartz powder treated with adhesion promoter r-aminopropylsilane

Nylon 6,6 30 % quartz powder treated with y-aminopropylsilane adhesion promoter

0.5 % Zn stearate

0.5 % Zn stearate / 2.0 % caprolactam

0.5 % Zn stearate / 2.0 % caprolactam

0.3 % Ca stearate / 2.5 % caprolactam

0.5 % Zn stearate

0.5 % Zn stearate / 2.0 % caprolactam

300 ⁰ C 295 ° C 260 ⁰ C

300 ⁰ C

260 ⁰ C

290 ⁰ C 268 ° C

not to get a good finish

310 ¹

28Ο

⁰ C

CO OO CaJ Ol

Claims (2)

- 5 - O.Z. jo 127 claims 1. Molding compositions made from polyamides and mineral fillers, characterized in that they contain 0.1 to 2.0 percent by weight of metal salts of long-chain carboxylic acids and 0.5 to 4.0 percent by weight of lactams. 2. Molding compositions according to claim 1, characterized in that they contain 0.2 to 1.0 percent by weight calcium or zinc stearate and 1.5 to 2.5 percent by weight caprolactam. BASF Aktiengesellschaft 50-9817 / 0945